Caulking gun



FIG. 1 is a right side elevational view on a reduced scale of a caulking gun showing our new design, the broken line showing is for illustrative purposes only and forms no part of the claimed design;

FIG. 2 is a right side elevational view the opposite side being a mirror image;

FIG. 3 is a front elevational view;

FIG. 4 is a rear elevational view;

FIG. 5 is a top plan view; and,

FIG. 6 is a bottom plan view. 

The ornamental design for a caulking gun, as shown and described. 